NASA 3D Prints First Rocket Part Composed of Two Metals

— September 23, 2017

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Advances in 3D printing have been slow to replace traditional manufacturing, but NASA is looking toward the technology as a way to fabricate parts for rockets. It’s already experimented with rocket components that were 3D printed from a single metal, but now it’s testing a process for printing in two different alloys. Using an advanced laser printing method, the agency has produced a bi-metallic rocket igniter that really works.

As the name implies, a rocket igniter is used to initiate a rocket engine’s start sequence. It’s a surprisingly complex part that’s difficult to make, so it’s an ideal candidate for 3D printing. However, you can’t make a rocket igniter out of a single metal. In traditional manufacturing, these components are produced using a process called brazing. The two different metal components are melded together using a filler material that locks them into place when the component is heated.

If you could find a way to make the part in a single step, you’d save a lot of time and money. NASA’s Marshall Space Flight Center in Huntsville, Alabama worked with a local engineering firm called ERC Inc. to make the prototype igniter. A unique hybrid 3D printer was used to build the part out of copper alloy and Inconel (a nickel-chromium alloy).

The printer uses a process called automated blown powder laser deposition. Like a standard 3D printer, this process allows engineers to lay down material one layer at a time. Powdered metal is fed into the build area as a focused laser heats it to produce a solid mass, a process called sintering. Using this printer, NASA gets a single part instead of four separate parts that need to be brazed.

The igniter is about 10 inches tall and 7 inches wide, but the 3D printing technology makes it easy to scale the design up or down. Changes to the interior can also be done without retooling machinery.

That all sounds great, but does the igniter work? That’s a resounding “yes.” NASA has test fired the prototype more than 30 times to prove it’s fully functional. After the test firings, researchers at the University of Alabama dissected the igniter to see how the bi-metallic structure held up. This analysis showed that the two metals were inter-diffused—the bond between the two metals is integral to the structure. That means the bond is incredibly strong. NASA plans to continue working toward 3D printing some rocket parts in its upcoming rocket engines, like those used in the Space Launch System.